Radio appliance



Aug. 4, 1931. o. E. MARVEL 1,817,443

RADIO APPLIANCE Filed May 6, 1927 1N VEIVTOR I A TTO-RNE Y Patented Aug. 4, 1931 UNITED STATES PATENT OFFICE ORIN E. MARVEL, OF DAYTON, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO GENERAL MOTORS RADIO CORPORATION, OF DAYTON, OHIO, A CORPORATION OF OHIO RADIO APPLIANCE Application filed May 6,

This invention relates to an electrical appliance for use in isolating undesired high frequency electrical oscillations.

One object of the invention is to provide an electrical appliance adapted to permit the passage of low frequency or direct currents, but to effectively isolate and choke the passage of high frequency oscillations such as occur at audio or radio frequencies.

A further object of the invention is to provide an electrical appliance, through which power may be transmitted from or to a portion of the line, the appliance being adapted to shield the portion of the line to which it is connected from undesired high frequency oscillations, such as those which occur at radio or audio frequencies.

The electrical oscillations which are gen erated in an electric commutator motor for example, or in any electrical apparatus in 'which an electric spark is produced are of such nature that they seriously interfere with radio reception if the radio receiving set is power is supplied to the apparatus, and the line then becomes a miniature broadcasting station resulting in a distribution of the undesired frequencies and disturbing oscilla tions through the surrounding air to any neighboring radio receiving set. It is an object of the invention therefore to permit the effective isolation of these undesired electrical oscillations so that their disturbing effect is reduced and practically removed.

Further objects and advantages of the invention will be apparent from the following description, the accompanying claims, and in the drawings, wherein the preferred embodiment of the invention is fully set fort-h.

In the drawings Fig. 1 is a diagrammatic showing of the electrical connections by which the appliance is connected to an electrical apparatus and to the line;

Fig. 2 is a central section through the winding of the appliance;

1927. Serial No. 189,313.

Fig. 3 is a central vertical section through the appliance;

Fig. 4- is a plan view of the same; and

Fig. 5 is a plan view of the winding as it is mounted on the condensers.

Referring more particularly to the drawings by reference numerals in which like numerals represent corresponding parts in the various views, the casing 10 contains the essential electrical parts of the apparatus. This casing, as shown, consists of a substantially rectangular can of nonmagnetic material such as sheet lead, the bottom of which is closed by a lead bottom plate 11, suitably connected at its periphery to the bottom of the side walls of the casing. A mounting strap may be provided on the side of the easing as shown. Within the casing and suitably sealed by a sealing compound 12 are mounted the various electrical parts of the apparatus. The sealing compound may be any suitable insulating compound which is capable of hardening after being poured.

The coil, shown in Fig. 2, consists of two windings designated! generally 13 and 14 which are wound about the two condensers 15 and 16, which have a length slightly exceeding the length of the coil. The two condensers when placed side by side form :1 rectangular elongated core which is entirely free from any magnetic material, such as iron or steel. On this core are wound the two windings 13 and 14, the windings being constructed of insulatedwire of snfiicient size to carry power currents, which are adapted to flow through them. The windings 13 and 14 are applied sininltaneously so that each layer of the coil consists of a number of turns of both of the windings; with a turn such as 20 of the winding 13 immediately adjacent and between the turns 21 and of the winding 14. Thus each turn of one winding for any particular layer of the coil has on each side of it a turn of the other winding. The windings are appliedsimultaneously and after winding on one complete layer as from the left to the right as shown in Fig. 2, the second layer is applied continuously without interrupting the operation by applying the various turnsv from 1 the other.

right to left. The coil as shown consists of four layers, each layer o't which applied in the same manner as the innermost layer, so that every turn of the coil is provided on each side thereof in the same layer with a turn of the other winding of the coil, and the ditl'erent layers a e also arranged so that a turn of one winding is adjacent turns of the other winding o'tvother layers. A numher 01'' separate windings may be provided,

; of the turns of one winding is atlected by the inductance of the other or trequcno of oscillation of a value greatly in exec at the normal power current trequencies. The two windings 13 and 111- are electrically insulatml i from one another and their ends are free from direct electrical interconnection. These two windings are connected so that they carry line current from the alternating or direct current supply line 30, the side 31 of .1 which is connected to the end 26 ot the winding 13 and the side 32 of which is connected to the end 28 of the winding 1%. The other two ends 25 and 27 of the windii are connected, as shown across a current consuming electrical apparatus capable of producing or tending to produce electrical oscillations of an undesired high frequency which might interfere with radio reception. Such an apparatus 33 is supplied with power from the line 30, the line currents flowing through the two windings ot the appliance as each winding is connected in series with one side oi the line. The two condensers 15 and 16 which are interconnected by the two wires l 35 and 36 to a common ground connection 37 for the ground are connected across the motor side of the two windings 13 and 14-. These two condensers are preferably oit equal value so that a path is pro 'ided from each side of the appliance to the ground through which the high frequency currents may pass.

The two windings 13 and 14 are so connected to the line and to the supply terminals of the motor or other apparatus that the power current normally flowing through the turns of the winding 13 travels in an opposite direction, at any instant, to the normal power current in the adjacent portions of i the other winding 14. Thus if a particular turn portion 20 ol the winding 13 carries current flowing away or downward on the up per side of the coil, then the two turns 21 and 22 of winding 14 will carry the line current on the opposite side of the line which passes through the coil 14, and the direction of this current in both the turns 21 and 22 will be upward or generally opposite to the current in the portion 20. At the low frequency of the power currents such as the present 60 cycle per second frequency, the mutual and self inductance of the windings will be insuflicient to cause any very material hindrance to the passage of the power currents through them. However, at audio and radio frequencies obtained in radio signalling which would tend to be set up by a commutator motor or an electrical arc of any kind, the instantaneous current which tends to flow through one winding from the electrical apparatus in which it is generated will be immediately opposed in its passage through the coil by a corresponding opposite bucking etl'ect of the other winding. The close proxin iity of the various turns 01' the two windings and the manner in which they are wound side by side has been found to cause a choke or bucking effect of one winding on the other for the passage of the high frequency interfering radio and audio oscillations.

The high frequency interfering oscillations which originate within the current consum ing apparatus 33 are blocked or choked in their attempt to pass through the windings 13 and 14 to the power line 30, and are dissipated by traveling through the condensers 15 and 16 and to the ground 38. These condensers provide a convenient path for the high frequency currents without, however, permitting the passage of the low frequency power currents. The manner in which the windings 13 and 14 are arranged with the individual turns of one winding situated between and adjacent the turns of the other winding throughout the entire coil,

provides a large distributed capacity effect between the windings so that any of the high frequency interfering oscillations which should find their way into the windings would pass through this distributed capacity from one winding to the other and thus he prevented from passing out to the line 30. The passage of the high frequency oscillations to the line 30 is of course undesirable as this line forms a part of a large net work of wires which, due to their extent would cause a c011- siderablc radiation of interfering waves which would be very objectionable to the operation of radio receiving sets and the like. The distributed mutual capacity ofthe windings 13 and 14 together with the condenser path through the condensers 15 and 16 t0 the ground thus form in etlect short circuits of low impedance which isolate the interfering high frequency currents and prevent their passage out to the power line.

The two windings 13 and 14 and the condensers 15 and 16 are adapted to be connected in their proper relationship to the line and to the current consuming apparatus by means of terminals as shown in Figs. 3 and 4. The condenser wires and 36 which are connected together at 37, are connected to the terminal wire 40 which extends through an insulating bushing 41 at the center of the top cover 42 of the casing. This top cover is provided with four other holes at its corner portions through which the four insulating bushings 48, 44, and 46 extend. The bushings 43 and 44 provide passages for the terminal wires 26 and 25 respectively, at the ends of the winding 13. The bushings 45 and 46 provide for the passage of the terminal wires 26 and 28 of the winding 14. The two wires 26 and 28 are adapted to be connected to the power line and the two wires 25 and 27 to the load or current consuming apparatus. The central wire 40 is of course adapted to be i attached to the ground to form a passage direct to the ground for any high frequency interfering currents which may be on either side of the line.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. An electrical appliance for use in shielding undesired electrical oscillations from an electrical apparatus comprising electrical condensers for by-passing undesirable oscillations, and a pair of windings arranged with their coils closely adjacent one another, the windings being adapted to be connected to a power supply line and to an electrical apparatus so that one winding supplies current from one side of the line with the current flow through an individual turn in an opposite direction at any instant to the current flowing in a closely adjacent turn of the other winding.

2. A radio appliance adapted to be used in shielding undesired electrical oscillations generated from an electrical apparatus comprising a pair of windings arranged closely adjacent and in mutual inductive relationship, said windings being adapted to carry the power currents in opposite sides of the line, and a condenser connected to an end of one of the windings and adapted to be connected at its other end to the ground, a second condenser connected to the other Winding and to the first condenser, said condensers being contained within the said windings.

3. A radio appliance adapted to be used in shielding undesired electrical oscillations from an electrical apparatus comprising a pair of windings arranged closely in a common flux circuit so that each has an inductive efi'ect on the other, said windings being adapted to carry the power currents from opposite sides of the line, a condenser connected to an end of one of the windings and adapted to be connected at its other end to the ground, said condenser being contained within the windings, an enclosing casing in which the windings and the condenser are sealed, and condenser and winding terminals at an end of said casing.

4. An electrical appliance for use in shielding undesired electrical oscillations from an electrical apparatus comprising a pair of windings arranged with the individual turns of one winding closely adjacent the individual turns of the other winding, said windings being adapted to be connected to carry the currents supplied from opposite sides of the line so that the direction of current flow through a turn of one windin is opposite the direction of normal current fiow in an adjacent turn of the other winding at any instant, said windings providing a capacity path for high frequency currents from one winding to the other, a pair of condensers on which said windings are arranged, the condensers and the windings being substantially free of magnetic metal, and an enclosing casing in which said windings and condensers are sealed.

5. In combination, a power line, a motor, 3

and an electrical appliance for shielding undesired high frequency oscillations generated in the motor comprising a pair of relatively insulated windings arranged with their coils close together on anon-magnetic core so that the turns of each winding mutually aflj ect the induction of the other winding to a substantial degree, one winding connected from one side of the line to one side of the motor and the other winding connected from the other side of the line to the other side of the motor carrying the full motor load so that a normal power current flow in a portion of one winding is in an opposite direction at any instant to the flow in the adjacent portion of the 1 other winding, a condenser connected to an end of one of the windings, a second condenser connected to an end of the other winding, the two condensers being connected together and to the ground and connected between the windings and the motor.

In testimony whereof I hereto afiix my signature.

ORIN E. MARVEL. 

